The control of attention is a basic skill, essential not only for cognitive tasks but for adaptive action generally. Two system controlling attention appear in the first 5 years of life. An orienting/investigative system emerges in the first 6 months; attention in this system is sensitive to novelty and habituates rapidly. A higher-level, goal-oriented system emerges at the end of the first year and natures throughout the preschool years; it allows attention to be governed by plans and involves the control of lower-level processes in the service of complex sequenced activity. The goal of this project is to learn more about focused visual attention and distractibility during early development. The specific aims of the project are 1) to further define and refine the behavioral measure of focused attention; and 2) to test several working hypotheses; a) focused visual attention involves a narrowing of selectivity in both perception and action; b) habituation to distracting events reduces distraction and supports focused attention; c) some destructors increase the amount of children's focused attention over non-distraction comparisons, due either to increased arousal and/or narrowing of the visual field; and d) with age, distractibility will decrease. Several cross-sectional studies are proposed in which children at 10, 26, and 42 months will be observed during free play with toys in the presence or absence of destructors. The location, type, and timing of destructors will vary, with the expectation that destructors located in the periphery will be responded to less, especially when the children are focused on the toys at the onset of the destructor. Children are focused on the toys at the onset of the destructor. Children exposed to destructors, particularly those in the periphery, should focus more than those not exposed because habituation to the destructors will enhance narrowed selectivity. The results should have important implications for how young children deploy attention in complex and stimulating environments and may help in our understanding of early attention deficits.